US 7967339 B2
A safety belt buckle presenter adapted for use with a translatable buckle includes an active material element operable to undergo a reversible change when exposed to an activation signal, wherein the element is drivenly coupled to the buckle, and configured to cause the buckle to translate between deployed and stowed positions as a result of the change.
1. An autonomous safety buckle presenter adapted for use with a structure, said presenter comprising:
a buckle translatably connected to the structure, so as to be caused to achieve deployed and stowed positions;
an actuator including at least one active material element operable to undergo a reversible change when exposed to an activation signal, said actuator being drivenly coupled to the buckle, such that the buckle is caused to translate to one of said deployed and stowed positions, as a result of the change; and
a latching mechanism configured to engage the buckle in said one of the positions, and configured to hold the buckle in said one of the positions when the change is reversed.
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11. An autonomous safety buckle presenter adapted for use with a structure, said presenter comprising:
a buckle translatably connected to the structure, so as to be caused to achieve deployed and stowed positions; and
an actuator including at least one active material element operable to undergo a reversible change when exposed to an activation signal,
said actuator being drivenly coupled to the buckle, such that the buckle is caused to translate to one of said deployed and stowed positions, as a result of the change,
wherein the actuator further includes a strain relief mechanism.
12. The presenter as claimed in
1. Technical Field
This disclosure generally relates to safety belt buckles and more particularly, to active material based safety belt buckle presenters and methods of manipulating a buckle utilizing active material actuation.
2. Background Art
Safety belt buckles have long been developed as part of safety systems used, for example, in automotive applications. These systems typically include an insertable structure (or “tongue”) configured to mate with the afore-mentioned buckle when inserted therein, so as to result in a fastened clasp. A continuous belt formed in part by the clasp provides a surrounding restraint that protects a user, for example, during sudden stop automotive conditions. Of concern, however, are the fixed configurations traditionally presented by these systems. More particularly, it is appreciated that conventional buckles are either in a constant readily accessible, but always visible position, or a more hidden, but difficult to reach position relative to the user.
In response to the afore-mentioned concerns, the present invention recites an active material based safety belt buckle presenter configured to selectively cause the buckle to translate between deployed and stowed conditions. That is to say, the inventive buckle presenter is operable to stow the buckle when it is not needed, and to automatically present the buckle when desired. As such, the invention is useful for aiding physically challenged users (e.g., the disabled, elderly, youth, etc.) to fasten their seat belts, and serves to remind and increase convenience for all users.
The use of active material actuators in lieu of mechanical devices such as solenoids, servo-motors, and the like, minimize the complexity associated with automation. Moreover, the use of active materials generally provides a lighter weight alternative, minimizes packaging space, and reduces noise both acoustically and with respect to electromagnetic field (EMF) outputs.
Thus, the invention generally concerns an autonomous safety buckle presenter adapted for use with a fixed structure, such as a passenger seat of a vehicle. The presenter includes a buckle translatably connected to the structure, so as to be caused to achieve deployed and stowed positions, and an actuator including at least one active material element operable to undergo a reversible change when exposed to an activation signal. The actuator is drivenly coupled to the buckle, such that the buckle is caused to translate to one of said deployed and stowed positions, as a result of the change. The invention further includes a source operable to generate the signal, so as to expose the element thereto, and at least one sensor configured to detect a condition, and communicatively coupled to the actuator and source. The sensor and source are cooperatively configured to generate the signal only when the condition is detected.
Other aspects and advantages of the present invention, including the employment of a shape memory alloy wire, and other active materials during actuation, latching mechanisms for presenting a zero-power hold, and various configurations of active-material based presenters will be apparent from the following detailed description of the preferred embodiment(s) and the accompanying drawing figures.
A preferred embodiment(s) of the invention is described in detail below with reference to the attached drawing figures, wherein:
The present invention presents an active material based safety belt buckle presenter 10 and methods of selectively deploying and stowing a safety belt buckle 12 utilizing active material actuation. As shown in
I. Active Material Discussion and Function
As used herein the term “active material” shall be afforded its ordinary meaning as understood by those of ordinary skill in the art, and includes any material or composite that exhibits a reversible change in a fundamental (e.g., chemical or intrinsic physical) property, when exposed to an external signal source. Thus, active materials shall include those compositions that can exhibit a change in stiffness properties, shape and/or dimensions in response to the activation signal, which can take the type for different active materials, of electrical, magnetic, thermal and like fields.
Suitable active materials for use with the present invention include but are not limited to shape memory materials such as shape memory alloys, and shape memory polymers. Shape memory materials generally refer to materials or compositions that have the ability to remember their original at least one attribute such as shape, which can subsequently be recalled by applying an external stimulus. As such, deformation from the original shape is a temporary condition. In this manner, shape memory materials can change to the trained shape in response to an activation signal. Exemplary active materials include the afore-mentioned shape memory alloys (SMA) and shape memory polymers (SMP), as well as shape memory ceramics, electroactive polymers (EAP), ferromagnetic SMA's, electrorheological (ER) compositions, magnetorheological (MR) compositions, dielectric elastomers, ionic polymer metal composites (IPMC), piezoelectric polymers, piezoelectric ceramics, various combinations of the foregoing materials, and the like.
Shape memory alloys (SMA's) generally refer to a group of metallic materials that demonstrate the ability to return to some previously defined shape or size when subjected to an appropriate thermal stimulus. Shape memory alloys are capable of undergoing phase transitions in which their yield strength, stiffness, dimension and/or shape are altered as a function of temperature. The term “yield strength” refers to the stress at which a material exhibits a specified deviation from proportionality of stress and strain. Generally, in the low temperature, or martensite phase, shape memory alloys can be plastically deformed and upon exposure to some higher temperature will transform to an austenite phase, or parent phase, returning to their shape prior to the deformation. Materials that exhibit this shape memory effect only upon heating are referred to as having one-way shape memory. Those materials that also exhibit shape memory upon re-cooling are referred to as having two-way shape memory behavior.
Shape memory alloys exist in several different temperature-dependent phases. The most commonly utilized of these phases are the so-called Martensite and Austenite phases discussed above. In the following discussion, the martensite phase generally refers to the more deformable, lower temperature phase whereas the austenite phase generally refers to the more rigid, higher temperature phase. When the shape memory alloy is in the martensite phase and is heated, it begins to change into the austenite phase. The temperature at which this phenomenon starts is often referred to as austenite start temperature (As). The temperature at which this phenomenon is complete is called the austenite finish temperature (Af).
When the shape memory alloy is in the austenite phase and is cooled, it begins to change into the martensite phase, and the temperature at which this phenomenon starts is referred to as the martensite start temperature (Ms). The temperature at which austenite finishes transforming to martensite is called the martensite finish temperature (Mf). Generally, the shape memory alloys are softer and more easily deformable in their martensitic phase and are harder, stiffer, and/or more rigid in the austenitic phase. In view of the foregoing, a suitable activation signal for use with shape memory alloys is a thermal activation signal having a magnitude to cause transformations between the martensite and austenite phases.
Shape memory alloys can exhibit a one-way shape memory effect, an intrinsic two-way effect, or an extrinsic two-way shape memory effect depending on the alloy composition and processing history. Annealed shape memory alloys typically only exhibit the one-way shape memory effect. Sufficient heating subsequent to low-temperature deformation of the shape memory material will induce the martensite to austenite type transition, and the material will recover the original, annealed shape. Hence, one-way shape memory effects are only observed upon heating. Active materials comprising shape memory alloy compositions that exhibit one-way memory effects do not automatically reform, and will likely require an external mechanical force to reform the shape.
Intrinsic and extrinsic two-way shape memory materials are characterized by a shape transition both upon heating from the martensite phase to the austenite phase, as well as an additional shape transition upon cooling from the austenite phase back to the martensite phase. Active materials that exhibit an intrinsic shape memory effect are fabricated from a shape memory alloy composition that will cause the active materials to automatically reform themselves as a result of the above noted phase transformations. Intrinsic two-way shape memory behavior must be induced in the shape memory material through processing. Such procedures include extreme deformation of the material while in the martensite phase, heating-cooling under constraint or load, or surface modification such as laser annealing, polishing, or shot-peening. Once the material has been trained to exhibit the two-way shape memory effect, the shape change between the low and high temperature states is generally reversible and persists through a high number of thermal cycles. In contrast, active materials that exhibit the extrinsic two-way shape memory effects are composite or multi-component materials that combine a shape memory alloy composition that exhibits a one-way effect with another element that provides a restoring force to reform the original shape.
The temperature at which the shape memory alloy remembers its high temperature form when heated can be adjusted by slight changes in the composition of the alloy and through heat treatment. In nickel-titanium shape memory alloys, for instance, it can be changed from above about 100° C. to below about −100° C. The shape recovery process occurs over a range of just a few degrees and the start or finish of the transformation can be controlled to within a degree or two depending on the desired application and alloy composition. The mechanical properties of the shape memory alloy vary greatly over the temperature range spanning their transformation, typically providing the system with shape memory effects, superelastic effects, and high damping capacity.
Suitable shape memory alloy materials include, without limitation, nickel-titanium based alloys, indium-titanium based alloys, nickel-aluminum based alloys, nickel-gallium based alloys, copper based alloys (e.g., copper-zinc alloys, copper-aluminum alloys, copper-gold, and copper-tin alloys), gold-cadmium based alloys, silver-cadmium based alloys, indium-cadmium based alloys, manganese-copper based alloys, iron-platinum based alloys, iron-platinum based alloys, iron-palladium based alloys, and the like. The alloys can be binary, ternary, or any higher order so long as the alloy composition exhibits a shape memory effect, e.g., change in shape orientation, damping capacity, and the like.
Thus, for the purposes of this invention, it is appreciated that SMA's exhibit a modulus increase of 2.5 times and a dimensional change of up to 8% (depending on the amount of pre-strain) when heated above their Martensite to Austenite phase transition temperature. It is appreciated that thermally induced SMA phase changes are one-way so that a biasing force return mechanism (such as a spring) would be required to return the SMA to its starting configuration once the applied field is removed. Joule heating can be used to make the entire system electronically controllable. Stress induced phase changes in SMA are, however, two way by nature. Application of sufficient stress when an SMA is in its Austenitic phase will cause it to change to its lower modulus Martensitic phase in which it can exhibit up to 8% of “superelastic” deformation. Removal of the applied stress will cause the SMA to switch back to its Austenitic phase in so doing recovering its starting shape and higher modulus.
Ferromagnetic SMA's (FSMA's), which are a sub-class of SMAs, may also be used in the present invention. These materials behave like conventional SMA materials that have a stress or thermally induced phase transformation between martensite and austenite. Additionally FSMA's are ferromagnetic and have strong magnetocrystalline anisotropy, which permit an external magnetic field to influence the orientation/fraction of field aligned martensitic variants. When the magnetic field is removed, the material may exhibit complete two-way, partial two-way or one-way shape memory. For partial or one-way shape memory, an external stimulus, temperature, magnetic field or stress may permit the material to return to its starting state. Perfect two-way shape memory may be used for proportional control with continuous power supplied. One-way shape memory is most useful for rail filling applications. External magnetic fields are generally produced via soft-magnetic core electromagnets in automotive applications, though a pair of Helmholtz coils may also be used for fast response.
Shape memory polymers (SMP's) generally refer to a group of polymeric materials that demonstrate the ability to return to a previously defined shape when subjected to an appropriate thermal stimulus. Shape memory polymers are capable of undergoing phase transitions in which their shape is altered as a function of temperature. Generally, SMP's have two main segments, a hard segment and a soft segment. The previously defined or permanent shape can be set by melting or processing the polymer at a temperature higher than the highest thermal transition followed by cooling below that thermal transition temperature. The highest thermal transition is usually the glass transition temperature (Tg) or melting point of the hard segment. A temporary shape can be set by heating the material to a temperature higher than the Tg or the transition temperature of the soft segment, but lower than the Tg or melting point of the hard segment. The temporary shape is set while processing the material at the transition temperature of the soft segment followed by cooling to fix the shape. The material can be reverted back to the permanent shape by heating the material above the transition temperature of the soft segment.
For example, the permanent shape of the polymeric material may be a wire presenting a substantially straightened shape and defining a first length, while the temporary shape may be a similar wire defining a second length less than the first. In another embodiment, the material may present a spring having a first modulus of elasticity when activated and second modulus when deactivated.
The temperature needed for permanent shape recovery can be set at any temperature between about −63° C. and about 120° C. or above. Engineering the composition and structure of the polymer itself can allow for the choice of a particular temperature for a desired application. A preferred temperature for shape recovery is greater than or equal to about −30° C., more preferably greater than or equal to about 0° C., and most preferably a temperature greater than or equal to about 50° C. Also, a preferred temperature for shape recovery is less than or equal to about 120° C., and most preferably less than or equal to about 120° C. and greater than or equal to about 80° C.
Suitable shape memory polymers include thermoplastics, thermosets, interpenetrating networks, semi-interpenetrating networks, or mixed networks. The polymers can be a single polymer or a blend of polymers. The polymers can be linear or branched thermoplastic elastomers with side chains or dendritic structural elements. Suitable polymer components to form a shape memory polymer include, but are not limited to, polyphosphazenes, poly(vinyl alcohols), polyamides, polyester amides, poly(amino acid)s, polyanhydrides, polycarbonates, polyacrylates, polyalkylenes, polyacrylamides, polyalkylene glycols, polyalkylene oxides, polyalkylene terephthalates, polyortho esters, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyesters, polylactides, polyglycolides, polysiloxanes, polyurethanes, polyethers, polyether amides, polyether esters, and copolymers thereof. Examples of suitable polyacrylates include poly(methyl methacrylate), poly(ethyl methacrylate), ply(butyl methacrylate), poly(isobutyl methacrylate), poly(hexyl methacrylate), poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methyl acrylate), poly(isopropyl acrylate), poly(isobutyl acrylate) and poly(octadecyl acrylate). Examples of other suitable polymers include polystyrene, polypropylene, polyvinyl phenol, polyvinylpyrrolidone, chlorinated polybutylene, poly(octadecyl vinyl ether) ethylene vinyl acetate, polyethylene, poly(ethylene oxide)-poly(ethylene terephthalate), polyethylene/nylon (graft copolymer), polycaprolactones-polyamide (block copolymer), poly(caprolactone) dimethacrylate-n-butyl acrylate, poly(norbornyl-polyhedral oligomeric silsequioxane), polyvinylchloride, urethane/butadiene copolymers, polyurethane block copolymers, styrene-butadiene-styrene block copolymers, and the like.
Thus, for the purposes of this invention, it is appreciated that SMP's exhibit a dramatic drop in modulus when heated above the glass transition temperature of their constituent that has a lower glass transition temperature. If loading/deformation is maintained while the temperature is dropped, the deformed shape will be set in the SMP until it is reheated while under no load under which condition it will return to its as-molded shape. While SMP's could be used variously in block, sheet, slab, lattice, truss, fiber or foam forms, they require continuous power to remain in their lower modulus state. Thus, they are suited for reversible shape setting of the insert 10.
Suitable piezoelectric materials include, but are not intended to be limited to, inorganic compounds, organic compounds, and metals. With regard to organic materials, all of the polymeric materials with non-centrosymmetric structure and large dipole moment group(s) on the main chain or on the side-chain, or on both chains within the molecules, can be used as suitable candidates for the piezoelectric film. Exemplary polymers include, for example, but are not limited to, poly(sodium 4-styrenesulfonate), poly (poly(vinylamine)backbone azo chromophore), and their derivatives; polyfluorocarbons, including polyvinylidenefluoride, its co-polymer vinylidene fluoride (“VDF”), co-trifluoroethylene, and their derivatives; polychlorocarbons, including poly(vinyl chloride), polyvinylidene chloride, and their derivatives; polyacrylonitriles, and their derivatives; polycarboxylic acids, including poly(methacrylic acid), and their derivatives; polyureas, and their derivatives; polyurethanes, and their derivatives; bio-molecules such as poly-L-lactic acids and their derivatives, and cell membrane proteins, as well as phosphate bio-molecules such as phosphodilipids; polyanilines and their derivatives, and all of the derivatives of tetramines; polyamides including aromatic polyamides and polyimides, including Kapton and polyetherimide, and their derivatives; all of the membrane polymers; poly(N-vinyl pyrrolidone) (PVP) homopolymer, and its derivatives, and random PVP-co-vinyl acetate copolymers; and all of the aromatic polymers with dipole moment groups in the main-chain or side-chains, or in both the main-chain and the side-chains, and mixtures thereof.
Piezoelectric materials can also comprise metals selected from the group consisting of lead, antimony, manganese, tantalum, zirconium, niobium, lanthanum, platinum, palladium, nickel, tungsten, aluminum, strontium, titanium, barium, calcium, chromium, silver, iron, silicon, copper, alloys comprising at least one of the foregoing metals, and oxides comprising at least one of the foregoing metals. Suitable metal oxides include SiO2, Al2O3, ZrO2, TiO2, SrTiO3, PbTiO3, BaTiO3, FeO3, Fe3O4, ZnO, and mixtures thereof and Group VIA and IIB compounds, such as CdSe, CdS, GaAs, AgCaSe2, ZnSe, GaP, InP, ZnS, and mixtures thereof. Preferably, the piezoelectric material is selected from the group consisting of polyvinylidene fluoride, lead zirconate titanate, and barium titanate, and mixtures thereof.
Electroactive polymers include those polymeric materials that exhibit piezoelectric, pyroelectric, or electrostrictive properties in response to electrical or mechanical fields. An example of an electrostrictive-grafted elastomer with a piezoelectric poly(vinylidene fluoride-trifluoro-ethylene) copolymer. This combination has the ability to produce a varied amount of ferroelectric-electrostrictive, molecular composite systems. These may be operated as a piezoelectric sensor or even an electrostrictive actuator.
Materials suitable for use as an electroactive polymer may include any substantially insulating polymer or rubber (or combination thereof) that deforms in response to an electrostatic force or whose deformation results in a change in electric field. Exemplary materials suitable for use as a pre-strained polymer include silicone elastomers, acrylic elastomers, polyurethanes, thermoplastic elastomers, copolymers comprising PVDF, pressure-sensitive adhesives, fluoroelastomers, polymers comprising silicone and acrylic moieties, and the like. Polymers comprising silicone and acrylic moieties may include copolymers comprising silicone and acrylic moieties, polymer blends comprising a silicone elastomer and an acrylic elastomer, for example.
Materials used as an electroactive polymer may be selected based on one or more material properties such as a high electrical breakdown strength, a low modulus of elasticity—(for large or small deformations), a high dielectric constant, and the like. In one embodiment, the polymer is selected such that is has an elastic modulus at most about 100 MPa. In another embodiment, the polymer is selected such that is has a maximum actuation pressure between about 0.05 MPa and about 10 MPa, and preferably between about 0.3 MPa and about 3 MPa. In another embodiment, the polymer is selected such that is has a dielectric constant between about 2 and about 20, and preferably between about 2.5 and about 12. The present disclosure is not intended to be limited to these ranges. Ideally, materials with a higher dielectric constant than the ranges given above would be desirable if the materials had both a high dielectric constant and a high dielectric strength. In many cases, electroactive polymers may be fabricated and implemented as thin films. Thicknesses suitable for these thin films may be below 50 micrometers.
As electroactive polymers may deflect at high strains, electrodes attached to the polymers should also deflect without compromising mechanical or electrical performance. Generally, electrodes suitable for use may be of any shape and material provided that they are able to supply a suitable voltage to, or receive a suitable voltage from, an electroactive polymer. The voltage may be either constant or varying over time. In one embodiment, the electrodes adhere to a surface of the polymer. Electrodes adhering to the polymer are preferably compliant and conform to the changing shape of the polymer. Correspondingly, the present disclosure may include compliant electrodes that conform to the shape of an electroactive polymer to which they are attached. The electrodes may be only applied to a portion of an electroactive polymer and define an active area according to their geometry. Various types of electrodes suitable for use with the present disclosure include structured electrodes comprising metal traces and charge distribution layers, textured electrodes comprising varying out of plane dimensions, conductive greases such as carbon greases or silver greases, colloidal suspensions, high aspect ratio conductive materials such as carbon fibrils and carbon nanotubes, and mixtures of ionically conductive materials.
Materials used for electrodes of the present disclosure may vary. Suitable materials used in an electrode may include graphite, carbon black, colloidal suspensions, thin metals including silver and gold, silver filled and carbon filled gels and polymers, and ionically or electronically conductive polymers. It is understood that certain electrode materials may work well with particular polymers and may not work as well for others. By way of example, carbon fibrils work well with acrylic elastomer polymers while not as well with silicone polymers.
II. Exemplary Configurations, Methods, and Applications
Turning to the structural configuration of the invention, there is shown various embodiments of an active safety belt buckle presenter 10 in
The presenter 10 includes an actuator 22 that utilizes at least one element 24 comprising an active material as described in Part (I). When the material is activated or deactivated, i.e., for example, where a thermally activated material is exposed to transformational heat energy or caused to undergo Joule heating by an electric current, a magnetorestrictive element is exposed to a magnetic field, or a stress activated element is exposed to a transformational force, the actuator 22 is configured to create a driving force. The actuator 22 is coupled to the buckle 12, such that the force is operable to cause the buckle 12 to translate to the deployed or stowed position. As shown in the illustrated embodiments, and discussed further below, the preferred presenter 10 further includes a biasing mechanism 26, such as a spring, weight, or hydraulic/pneumatic pressure system, a strain relief mechanism 28 configured to relieve stress/strain within the element 24 when deployment of the buckle 12 is otherwise blocked, and a latching mechanism 30.
In a first embodiment shown in
As illustrated, the strain relief mechanism 28 may include an extension spring 36 intermediately coupled between the wire 24 and structure 16 (
It is appreciated that the weight of the buckle 12 and strap 32 will cause their downward translation back to the stowed position (
As previously mentioned, the preferred presenter 10 further includes a latching mechanism (i.e., latch) 30. In
As also shown in
Thus, in this configuration, activation of the material and contraction of the wire 24, results in the compression of the spring 40 (
In another pivotal embodiment shown in
A return spring 40 is preferably attached to the weight 48 and strap 32 at or near the buckle end and configured to cause the weight 48 to re-traverse the axis, when the wire 24 is deactivated, thereby causing the return of the buckle 12 to the stowed position (
In a preferred embodiment, the spring 40 may itself be formed of shape memory alloy material in a normally (i.e., deactivated) austenitic state. As a result, the antagonistic SMA wires 24 and spring 40 are cooperatively configured such that thermal activation of the wires 24 causes a stress induced transformation of the spring 40 to the martensitic state. This reduces the modulus of the spring 40 as well as lengthens the spring material. When the wires 24 are deactivated, the spring 40 returns to the austenitic state, thereby increasing in modulus, and causing the weight 48 to return to the normal position.
When the wires 24 are activated and the slider 54 is caused to traverse the axis, the orientation of the spring 56 is changed such that the force vector causes an opposite moment about the axis. As such, the spring 56 is configured to produce a biasing force against the buckle 32 in both the stowed and deployed positions depending upon the positioning of the slider 54 relative to the axis. The preferred actuator 22 and spring 56 are cooperatively configured such that the spring 56 presents a majority of the deployment and stowage force necessary; as a result, it is appreciated that less active material (e.g., a lesser plurality of wires 24) may be utilized.
In yet another pivotal strap embodiment shown in
In another example, the strap 32 may be fixedly attached to the structure 16, but present a flexible, collapsing, telescoping, or the like mechanism or material, such that the buckle 12 is translatably attached to the structure 16. In
In another flexible strap embodiment shown in
When the wires 24 are deactivated, the weight of the buckle 12 causes the scissor 76 to collapse, and the buckle 12 to return to the stowed position. More preferably, an extension return spring 40, also connected to the distal and lower most joints, is provided to further bias the scissor 76 towards the collapsed condition, and the buckle 12 towards the stowed position.
In another collapsible strap configuration (
When activated, the SMA wire 24 contracts, causing the cable 86 to recede within a diametrically congruent opening defined by the portion 82. A strain relief mechanism 28 is preferably provided intermediate the wire 24 and structure 16, and accommodates the wire 24, when the buckle 12 and cable 86 are not able to recede. The compression spring 80 stores energy during activation, and works to bias the buckle 12 towards the deployed position. Finally, a latching mechanism 30 is preferably provided to hold the buckle 12 in the stowed position, until deployment is desired. More particularly, and as shown in
Finally, in a pivotal and collapsible embodiment, the presenter 10 presents a simplified configuration consisting of at least one SMA wire 24 wrapped around the pivot axis, p, defined by an axle, or stalk (
It is appreciated by those of ordinary skill in the art that other actuator configurations and/or active materials may be used in the present invention. For example, an active material rotary hinge, as disclosed in co-owned U.S. patent application Ser. No. 11/744,966 (incorporated by reference herein), may be used in conjunction with a pivotal strap 32. Other configurations include active material based torque tubes, shape memory polymer springs presenting differing activated and deactivated spring moduli, and active material actuation combined with gears, pulleys, ramps and other devices designed to provide mechanical advantage to the material.
In a preferred mode of operation, the active material element 24 is coupled to a signal source 96 (
More preferably, at least one sensor 100 operable to detect a condition of interest, is communicatively coupled and configured to send data to the controller 98. As such, the controller 98 and sensor 100 are cooperatively configured to determine when a buckle deployment situation occurs, either when the condition is detected, or a non-compliant condition is determined through further comparison to a predetermined condition threshold; for example, an occurrence may be found, where a force greater than 90 N (i.e., 20 lbs) is initially detected by a piezoelectric-based load sensor 100 (
The triggering condition may be the act of pulling the safety belt webbing 18, opening or closing a vehicle door 102, occupying the associative passenger seat 16, fastening or unfastening the clasping structure 20 and buckle 12, or turning the ignition switch 104 on or off. Once the element 24 is activated, the controller 98 is configured to discontinue the signal after a predetermined period (e.g., 10 seconds), so as to present sufficient opportunity for the user or occupant to fasten his or her seat belt. Alternatively, it is appreciated that a delayed return, resulting in an equivalent deployment period, may be accomplished by insulating the wires 24, such that cooling is retarded.
Ranges disclosed herein are inclusive and combinable (e.g., ranges of “up to about 25 wt %, or, more specifically, about 5 wt % to about 20 wt %”, is inclusive of the endpoints and all intermediate values of the ranges of “about 5 wt % to about 25 wt %,” etc.). “Combination” is inclusive of blends, mixtures, alloys, reaction products, and the like. Furthermore, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The modifier “about” used in connection with a quantity is inclusive of the state value and has the meaning dictated by context, (e.g., includes the degree of error associated with measurement of the particular quantity). The suffix “(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the colorant(s) includes one or more colorants). Reference throughout the specification to “one embodiment”, “another embodiment”, “an embodiment”, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.
Suitable algorithms, processing capability, and sensor inputs are well within the skill of those in the art in view of this disclosure. This invention has been described with reference to exemplary embodiments; it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to a particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.